A Soldier's Job (An Alternate Universe)
by ShweezyLiz
Summary: Has it really been 3 years since then? 3 years of walking through this deserted land. Huh, what happened back then? Oh right. I'm a soldier, a part of the 125th Fighter Squadron of the Marine Corps, serial number 528132. The name's Saitama.
1. Chapter 1

**PLEASE READ AUTHOR'S NOT**

 **A/N: Hey guys! So this is the second story that I posted here on this website, and if you're wondering what this fan fiction actually is, let me recap for you. This fan fiction is an AU, or an alternate universe** **fan fiction of One Punch Man. In this story, Saitama decides to be a soldier instead of a hero. And also, unlike in the anime, the other characters may be different than their counterparts unlike in the original. Think of this as an apocalyptic AU, since this story is similar to an apocalypse happening. Anyways I hope you guys enjoy this story! (This was an AU that I thought of in Tumblr)**

 **I do not own One Punch Man or its characters, OPM is originally made by ONE.**

* * *

 ** _The Strongest Man Alive_**

 ** _..._**

 _Has it really been 3 years since then?_

 _3 years of walking through this deserted land..._

 _Huh, what happened back then?_

 _Oh right..._

 _I'm a soldier, a part of the 125th Fighter Squadron of the Marine Corps, serial number 528132._

 _The name's Saitama._

 _I remember back then when this world was a world of peace and tranquility. It stayed like that, even before the day I was born. Back then, everything was normal. Back then, I used to have hair. I use to live in City Z, just a normal city like every other city. City Z was populated, always bustling with life, with good people and average services. I lived just around the outskirts of City Z, but I was near enough to pass by the supermarkets to buy for some groceries whenever I needed to. Needless to say, during my teenage years, I lived a normal life that an average teenager would._

 _Though, when I was a kid, I had always dreamt of becoming a soldier, just like my dad._

 _I always wanted to follow in my father's footsteps, to be honest I wanted to be a soldier because of him. His good heart inspired me to become just like him. So, my goal was to serve in the army. To protect those in need, and to fight for those who needed it._

 _After graduating high school, I immediately registered to be in the army. I was thrilled to find out that I was accepted and expected to be sent off to a nearby training camp. I was sent to the marine corps recruit training, mostly referred to as "boot camp" by me and my fellow recruits. The camp was located far out of the outskirts of City Z, I was farther than I thought I was. I spent 12-weeks in what I thought was gruesome, torturous training back then to serve in the Marine Corps. I had to throw out my 'civilian' mindset out the window, and instill discipline into my behaviour. It was hard, but I was determined to be a soldier._

 _My mother said that it was a bad habit of mine..._

 _Training was awful and gruesome, but in the end of it all I was deemed fit to serve in the army. And for the first time in my life, I felt accomplished, I felt that I had completed my goal, and that I was living it. At that time, I was able to feel victory. I had become the hero I had always dreamed of becoming..._

 _But then, it happened..._

 _The 'Omega Event'._

 _It happened on a normal Thursday afternoon, training went by swiftly, I completed the tasks that I was assigned to do every day. I was going through the normal routine as always._

 _But then a sudden alarm went off. At first I thought that it was another one of those surprise training drills if ever there was an emergency, but the frantic movement of soldiers and the sudden arrival of the general to the camp made me think otherwise. We were told to get into our fighting gears, get into our assigned squadrons and report to any nearby sergeants in the area about the current situation. I had no idea what was going on, and it seemed like my fellow colleagues had no idea what was going on as well._

 _That was then we all heard a sudden loud, animalistic roar. Everyone was stunned, but stood their ground. The loud roar continued, the sound intimidated me and I felt so small. Then, screams were heard and echoed through the camp. The screams were blood curdling, I couldn't help but cringe at the sound of it. The sound was followed by clicks and snaps of what I thought would be the sound of cracking bones and I felt an unpleasant shiver run up my spine at that very moment. I remember when the ground beneath my feet shook violently, and I fell to my knees and struggled to get up._

 _Then the sudden sound of the earth erupting echoed through the valley, I immediately shot up, and was scarred the moment my eyes met a large shadow looming above us._

 _A large four-legged like creature emerged from the earth among the mountains outside the training camp. It was the largest creature I had ever seen in my whole life. It looked similar to a praying mantis, its large shell was adorned with large spikes, its eyes were red, as red as blood, its antennas were as long as a plane. The creature was donned in black, and as it walked, the earth would shake beneath its weight. It towered over our fences, it was so big that the rays from the sun could no longer reach the earth due to its large body._

 _I remember the day that creature emerged from the earth, I remember the feeling of dread, fear and adrenaline run through my veins._

 _For the first time in my life I was scared._

 _And it all went downhill from there._

...

"Three years huh..." I sighed to myself, as I stared at the debris beneath my feet. I still wore the same marine corp outfit that I wore back then, when that very day happened. (of course I would occasionally wash it from time to time) With one last glance at the destroyed village behind me, I sighed and continued to trudge through the scattered debris, and into a grassy field ahead.

For 3 years I have been searching for any remaining human soldiers across the land.

For 3 years I have been searching for any squadrons left.

For 3 years I have been searching for a creature who would last more than one punch.

Yep, for the past 3 years ever since that event happened, I fought monsters that used to be way out of my league. It seemed that my constant fights with different monsters had boosted my strength. Because everyday, I would always encounter a monster one way or another. Sometimes, they would vary from creatures that would barely come to my height, to monsters that were bigger than the empire state building. And everyday, I would always struggle to take them down.

There were times when I fought with my gun or my blade, but most of the time I fought with my bare hands. I didn't know why I would always neglect to use my resources against my foes, but it seemed that it became a habit of mine. A habit that I got from my father.

After fighting various monsters for days and days, continuously every day, I had become strong.

I would always run about what I estimate to be around 10 kilometres everyday whenever a monster appeared and tried to chase me down.

During my free time, I would do 100 push ups, 100 squats and 100 sit-ups everyday, if you include the times whenever I would climb up a large monster, I always had to pull my body up.

It felt like hell, I felt like I would die any moment. I felt that I would either die from monsters, or die from exhaustion. But I kept going, even though my joints began making painful cracking noises whenever I ran, even when my arms could no longer lift my carbine, even when my legs would throb and ache agonizingly whenever I tried to run to my target, even when I felt like I would die or drop down at any moment I still kept on going. Everyday felt like you were being interrogated, it felt like you were being asked the same dreadful question over and over again. _When are you going to give up?_

But no matter what I didn't give up, I fought like hell to survive. I fought for those who couldn't even fight for themselves, and those who couldn't defend themselves.

Three years later, I noticed that all my hair fell off. But I had noticed a considerably large boost in my strength. Instead of relying on my firearms, I relied on my own brute strength. With one swift punch, I killed off any enemy in sight.

In the span of three years, I had gained the strength I never thought I could achieve but did. I exceeded my expectations and I exceeded my limits.

I gained the strength to defeat any enemies with merely one punch, and it came to the point that I didn't even need to put that much effort to fight.

But in exchange for strength, I realized that I lost something that made it essential to be _human._

Back when I hadn't gained this strength, I felt all kinds of emotions whirling inside me when I fought.

 _Dread_

 _Fear_

 _Rage_

 _Determination_

But now, all I need was one punch to end it. Now, I no longer felt anything whenever I fought a monster.

For a long time I felt empty inside.

Maybe it could have been the boredom from fighting, or the fact that I haven't seen a fellow soldier for such a long time. For a long time I have not heard from any other fellow soldier, besides myself. I would trudge through thick and thin to find any _human_ who served in the army.

That was my goal in the first place.

That was the _order_ given to me, personally by the general.

I am still a soldier, this was what I signed up for and is willing to do at all costs.

Even when I no longer felt emotions, I still have a job to do.

I am a _soldier..._


	2. The Lone Cyborg - Part 1

**_The Lone Cyborg_**

 ** _._**

 _It was just another day. Another day just like the rest…_

Saitama sighed to himself as he dusted off the dust from his carbine and changed the clip. He hated having his firearms covered in dirt, or any kind of suspended particles that he didn't like to have around him. But it couldn't be helped, he'd either have his arms covered in blood or bathed in dust. He wasn't a clean freak, but it was pretty normal to avoid such things.

After wiping off the dust off his carbine and uniform, he continued on with his daily routine.

 _Find the remaining squadrons._

That was his main objective that he had pinned in his head every day, a reminder that he needed it done.

He lazily trudged through the ruins once again, the remnants of the destroyed village in his wake had became a normal occurrence to him. In a world where monsters keep on emerging from the depths of the earth everyday, it became a normal thing to find ruins of pillaged villages or cities for Saitama. He didn't find it pleasant, but he had grown accustomed to the sight.

He looked down at his uniform, donned in dark shades of brown, green and yellow, his uniform was designed for camouflage, but when you are constantly surrounded by ruins and there were no longer any forests in sight, he was standing out in the open.

The sharp sound of cement and glasses crunched beneath his boots as he trudged through the ruins. So far there weren't any survivors among the ruins much to his dismay. Saitama figured that the people had already flee or evacuated from their towns and villages as soon as a monster appeared near the vicinity.

The sky was clear today, not a single cloud or a speck in the sky. It was another normal day, nothing exciting happened, another uninteresting creature was taken care of, and Saitama was bored once more.

After walking for what seemed like an eternity, Saitama had decided to stop. He had been blindingly walking for nearly an hour now, but Saitama had covered miles upon miles in three years, so this feeling was not new to him at all.

He found himself in a grassy plain, which led to a small river by the east. Taking off his gloves, Saitama sat down on a boulder just nearby, taking in the peaceful scent of his surroundings. It was quiet, the faint sounds of flowing water was soothing. Saitama found himself falling into a deep reverie, only to be interrupted by the sound of a bug. His eyes snapped open, his whole body tensed.

 _Bzzzzzzzzz_

A small black dot buzzed through the air that Saitama breathed. A vein became visible in his forehead. Seemingly, at the speed of light, he brought the end of his palms in between the small dot, a shockwave erupted from the sudden clap. Glaring at his palms, he watched as the fly buzzed its way out of his grip.

"Fucking mosquitos…" Satiama muttered through gritted teeth.

Clapping his hands together between the mosquito in an attempt to kill the damn thing, but the mosquito managed to escape his death grip more than once, only irritating him more.

 _I hate mosquitos..._

He had the strong urge to just whip out his carbine and attempt to shoot the damned spawn of satan, but he had to save ammunition, so instead, he reached for his back pocket and whipped out a small hand knife and chased after the small fly. But before he swung his knife, the fly had already flew away.

"HEY! COME BACK HERE! I'M NOT DONE WITH YOU YET!" He screamed while he blindly chased the fly, oblivious to the large city that he was headed to…

…

 _Bzzzzzz_

Screams rang throughout the city,

The sky darkened as an unknown cloud of dust covered the city, covering the land in shadows. A large swarm of mosquitos had approached the city, easily hovering over the towering buildings and skyscrapers. Sirens rang throughout the city as people scattered like ants throughout the roads, fleeing to get to safety. Civilians ran towards the nearest evacuation site, and soon enough, the streets were empty.

Although, anyone who wasn't able to get to safety immediately, faced an immediate and agonizing death.

The swarm would target the nearest living specimen in sight, and anyone caught in its wake had no chances of escape. A man, who happened to be at the wrong place at the wrong time, faced his fate. The mosquitos swarmed and surrounded the man, while he flailed and pleaded for help, before latching themselves onto the man, and sucking up all his blood. Once the swarm was done with its unsuspecting victim, it flew off, not before leaving a corpse.

The swarm then flew up into the sky, and pooled on one spot in the air, before revealing a woman whose body was largely an exoskeleton, and had an appearance as being partly insect and partly humanoid. She had wings of an insect which allowed her flight, her head resembled that of a mosquito's, while her limbs extended and end in twin hooks. She had a rather voluptuous figure.

"Come on you guys… That wasn't nearly enough…" She spoke, unsatisfied with the offer that her swarm had just given her.

"Go get some more for me!" She ordered, before noticing a presence not too far from her.

"Target acquired…" The said presence spoke, before firing a blast of fire at the winged beast, although, the fire completely unaffected the woman.

"I see…" Said the mysterious figure as he approached the girl.

The figure was hardly a man, or rather it once had the form of a man. His body mostly covered in a green uniform, while his limbs were not that of a human's. His body has an entirely mechanical body in the model of a man. His face seemed to look like that of a normal human's face, but only his fiery, golden eyes were visible through his dark grey mask that only covered the lower parts of his face and wore helmet.

Judging by the man's outfit, _it was a soldier._

"You make them suck the blood, then take it all for yourself…" The man speculated.

"You must be controlling the mosquitos via some sort of signal. That would explain their mysterious behavior." He continued, recalling the sight of the dried corpses and caracasses that he had discovered earlier before arriving into the scene.

"So if I were to get rid of you, the leader, would the swarm disperse too?" He concluded.

His response was only a simple laugh from the woman, "Our next meal is here. Go drain him dry." she ordered, completely ignoring the soldier's question.

Following as ordered, the swarm of mosquitos bolted towards the said man, surrounding him and completely blocking him from view of anyone who could witness the sight before them. Although, the man was completely unaffected, before saying, "Incinerate."

The swarm was suddenly engulfed by fire, and was immediately disintegrated in the sudden flames. The woman watched as her swarm of mosquitos were gone in an instant, leaving marks of the fire on the concrete streets, a look of shock was evident on her face.

"I am about to eliminate you. Stay where you are..." The man simply stated, reaching for his carbine that hung behind his back, before aiming at the winged-woman.

His name was Genos.

* * *

 **And that's all for now, and also just to let ya'll know, some chapters in these stories are going to be maybe shorter than the rest. Hehe…**

 **Anyways hope ya'll liked it.**


	3. The Lone Cyborg - Part 2

_**Heyo! I'm back again! Sorry if I wasn't able to upload a chapter yesterday, I got kinda busy, hehehe. Anyways just to remind some of you, this fanfiction might be different than the storyline in the original anime, like for example Saitama might have a different reaction to Genos unlike in the anime. That's all and here's the story!**_

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 _The Lone Cyborg Part 2_

 _..._

The sound of gunfire rang throughout the streets of the city as the cyborg jumped from building to building, aiming his carbine at the winged beast. His eyes zeroing in on his target as he fired several shots whilst sprinting. The woman dodged each bullet, before flying up higher into the sky.

Genos ran across the side of the building, using his thrusters that were fixed onto his limbs, blasted off into the sky, towards the said female. Throwing a punch at the woman, only to be dodged and jettisoned to the side, she threw her twin hooks at him, to which the cyborg blocked by his free arm. While the winged beast struggled to overpower him, Genos then powered his thrusters once more, generating energy onto his hands and firing at the beast, the explosion separating the two. Genos bolted back towards his target as soon as his feet touched the edge of the building, throwing another punch at her, to which the woman blocked before hammering him back down to the ground.

Quickly regaining his balance and firing beneath him to safely to land onto the ground. Grabbing his carbine once more, generating and transferring the energy mustered by his thrusters into his firearm, he aimed at the woman. "Incinerate," He spoke before pulling the trigger and firing continuous rounds at his target.

The winged beast dodged each incoming flaming bullets, making her way towards the cyborg whilst dodging each fire. She then bolted towards his right arm, completely ripping off the prosthetic limb from his torso, she then flew back up, the cyborg's right arm still hanging loosely on the now elongated horn from her head. She chuckled as she stared at the cyborg, who was missing his right arm.

"Maybe a leg next?" She giggled, but stopped as she then realized something. She looked down only to see both her legs were missing, "Wait, where are my legs?" She questioned as she stared at her lower limbs quizzically.

She turned just in time to see the cyborg throwing both her legs aside, facing the mosquito girl, seeing this, the woman scowled before flying away.

"Impossible." Genos spoke, aiming his carbine once more at the girl, generating its bullets before a large fireball was shot from his firearm towards the creature. Before the fireball made impact with her, a sudden swarm of mosquitos engulfed her, before setting ablaze.

"You cannot escape from me." Genos simply stated as he watched the swarm disintegrating into smoke.

Finally safe within the skies, the girl scowled in frustration, "What the hell is that guy? He's gonna get me if I don't do something."

She grinned as she looked down at the sight beneath her. The town seemed empty but she knew there were still living organisms outside of the city and within the city.

"The townspeople may all be hiding, but there are plenty of animals around." She chuckled as she recalled all of the dead carcasses of different animals that were left lying outside of the city. "Come little ones! Empty all your stored juices into me!" She ordered, another swarm, larger than the last, immediately complied and engulfed her once more, casting a large shadow upon the city.

Genos immediately spotting the said swarm, ran towards it, stopping just several feet from it. He then analyzed the swarm, gathering information from his target. Noticing that the swarm were not just giving her the blood for a food source, but also for power. Realizing this, he grabbed his carbine once more and charged yet another energy blast before aiming at the said swarm. _"I should put an end to this as soon as possible,"_ He thought as he zeroed in onto the swarm.

He was stopped midway when he heard a distant voice, "GET BACK HERE DAMMIT!"

Turning around, he saw a man donned in mostly green, holding what he assumed to be a pocket knife, chasing a mosquito…?

"YOU THINK YOU CAN RUN AWAY FROM ME?!" Saitama yelled once more in frustration as he chased down the fly.

" _What's with this guy?"_ Genos thought as he analyzed the man, as Saitama blindingly approached the cyborg.

"It's in my mouth! PFT! PFT! You littl-" Saitama groaned as he tried to spit out the said fly, before noticing the presence before him.

Saitama stared at the presence that stood just a few feet away from him. Immediately, his eyes darted towards the cyborg's uniform. It was donned in different shades of yellow and green, and he held an unrecognizable firearm in his left hand, but he seemed to missing a right arm. Saitama shook his head before noticing the swarm of mosquitos that was right above them.

"What… In the fuck?" Saitama muttered, immediately associating the swarm as flies.

"You over there." The cyborg called out, grabbing Saitama's attention immediately.

"Evacuate now. That swarm is conscious. If it senses you, it will immediately attack." Genos said sternly.

Saitama was only silent at this, although he completely ignored what the cyborg just said. No, he was too busy staring at the cyborg, completely dumbfounded. Recognizing the symbol on the cyborg's left arm, Saitama knew all too well what it was.

 _And it was what he was looking for._

"Hey… Aren't you… A sol-" Saitama stopped midway when he heard a sudden laughter that rang through the streets.

The two watched as the swarm grew bigger and bigger, before bolting out into different directions across the city. The swarm surrounded building, and completely covered and overran the streets, breaking and razing buildings completely. As the swarm grew in size, a sudden light suddenly erupted from within it, before the swarm completely engulfed by fire once again.

A large explosion erupted from the swarm, the sky was then decorated with red, yellow and orange. The fire raged and raged, flowing through the streets and into empty buildings like a raging river, the town turning into a flaming inferno.

Several minutes later, the fire began to die out, leaving scorch marks and ashes in its wake before it completely disintegrates.

"Since you spoke, I thought you would at least have human-level intelligence. But you were just a bug." Genos spoke up, slightly resting his left arm.

"You brought all the mosquitoes together into one, easy-to-burn, swarm. When I spotted you, I confirmed that there were no living beings within 500 metres. So I should have been free to fire away." Genos continued, before sudden realization hit him.

"Wait, that guy might ha-" He gaped, but was cutoff mid-sentence when he heard a sudden voice.

"Man… You saved me! That was amazing!" A voice commented from behind him, causing the cyborg's attention towards the said voice.

"What was that just now? You totally made them… _Bug_ out! Badum-tssh." Saitama joked, emphasizing on the word _bug._ Genos could only stare at the man in disbelief, he was still in one place, and somehow, his clothes still remained and firearms still remained. _(because why the fuck not, I need this for the plot)_

Saitama, thinking that the cyborg did not get the joke, spoke, "Oh. I was just trying to make a joke about the mosquitoes being bugs and you…Well..." He explained, whilst shrugging and shaking off the ashes off his helmet and uniform. A sudden maniacal laughter caught both of their attention, and Genos turned and saw the mosquito girl again.

Her appearance was different than last time, the woman had now a mix of dark and light shades of red that adorned her body, her wings were elongated, both of her legs were back and her twin hooks were longer and sharper than before.

"Idiot." She laughed as she flew down, admiring her new form.

"I no longer need the tiny ones, I mean." She chuckled before raising her arms and swung it towards a building. As soon as her hooks made contact with the building, it was completely razed and seemingly disappeared into thin air from the impact. Genos was befuddled at the sight as the sight as the mosquito girl demonstrated her strength and capabilities.

"Look… How strong I've become!" She grinned from ear to ear, before turning towards the cyborg, her face distorted into a psychotic expression.

She then bolted towards him in a flash of pink, before reappearing behind him, simply swinging her twin hooks at the cyborg's torso, completely slashing his lower abdomen.

The cyborg scowled before turning around to face the winged beast and threw a punch at her, only to be interrupted as he found himself in the air. The beast toying with him as she dashed towards the cyborg who was in mid-air, slashing him in different areas on his body, marking and damaging the cyborg's mechanical frame.

Genos found himself being toyed with by the beast, he was tossed and spun around in midair as if he was some kind of ragged doll. "Can't your punches kill a little mosquito? Weakling!" She mocked as she continued to ravage the cyborg with her attacks. Her laugh only taunting him more. The cyborg found himself unable to do anything to defend himself against the creature, realizing that she had already grown too powerful for him as he fell. His helmet and mask was damaged and was eventually torn off.

"I think… I'll have your head next!" She exclaimed as she then dashed towards him.

" _I let my guard down… There's no chance of winning…"_ The cyborg was free falling back down to the ground in a frightening velocity. _"All I can do is self-destruct…"_ He thought as he began to charge another energy blast, this time charging within him.

A blue, bright light gradually accumulated in size within the cyborg's torso, _"Forgive me… Doctor…"_ Was his last thought in his head as he awaited the beast's next attack.

The mosquito girl laughed maniacally once more as he neared the cyborg, only to be interfered when a hand suddenly made contact with her face, before the force of the slap completely obliterated her. Large amounts of blood splattered across a nearby building like paint being thrown onto an empty canvas. A sudden wave of wind shot through the cyborg as the ground shook beneath them, the force completely shaking the earth.

Genos was awestruck and dumbfounded at the sight before him before falling back to the ground, the blue light that emitted within him awhile ago was gone.

"Mosquitoes suck…" Saitama grinned as he made one more joke.

The sunlight found its way back onto the city, its gentle rays touched and illuminated the scorched and burnt streets, the cyborg finally got a better view of the man just behind him. He just couldn't believe his eyes at the man's actions.

Saitama dusted off the remnants of the mosquito girl off his gloved hands, checking if he's uniform was stained in any way he groaned in annoyance as he saw his chestplate had some slight stains of blood on it. Shrugging it off, he then approached the damaged cyborg, who now lays awestruck on the ground, his eyes never leaving the man. Saitama then stood before the cyborg, before noticing that the cyborg's mask and helmet no longer hid his face.

His face was that of a human's. And he looked young too…

"Hey…" Saitama said, immediately snapping the cyborg from his reverie.

"What's your name kid?" He questioned, his voice was different than before.

"Genos." The cyborg replied eagerly,

Saitama then knelt down beside the cyborg, "Need a hand?"

"Let me know your name..." Genos said, completely ignoring Saitama's offer.

"Its Saitama…" The man offered his name.

"Please make me your disciple!" Genos exclaimed eagerly, as soon as he got his name.

"Oh… Okay." Saitama said absent-mindedly.

He stared at the cyborg before realizing what he had just asked of him, "Eh?"

.

Saitama hummed as he trudged along the ruins of the city once more, this time, a companion in hand, literally.

He had just agreed to become Genos' teacher, without him thinking that much about it. _What did he just got himself into?_ Saitama sighed, Genos' left arm was around his shoulder, the young cyborg leaned onto him for support as the two walked towards the direction that Genos had pin pointed.

On Saitama's free hand, he held Genos' missing right arm.

As the two walked, he was bombarded with questions and statements by the teen,

"Saitama-Sensei, I appreciate what you have done sincerely," He says,

"Can you not call me Sensei?"

"Master!"

"Not that either,"

"Sensei it is then…"

"What?! No, don't call me th-"

"Sensei!"

"Ugh…"

Well, it looks like Saitama had made a friend. A friend that will _surely_ change his course in life...

* * *

 **Eyo! So that's all for now! Sorry if the chapters are short, I don't really have much time to do the whole episode so far and please forgive me for that! Well, hope ya'll like this chapter! :P**


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